In a conventional power conversion apparatus, an output from a first terminal of an AC power supply is connected to a reactor, and at the subsequent stage of the reactor, the AC side of an inverter circuit composed of a single-phase inverter is connected in series. The single-phase inverter in the inverter circuit is composed of a semiconductor switching device and a DC voltage source. In addition, first and second series circuits connected in parallel, each of which is composed of a short-circuit switch and a rectification diode connected in series to form an inverter, are connected between both terminals of a smoothing capacitor at the output stage. The middle point of the first series circuit is connected to an AC output line at the subsequent stage of the inverter circuit, and the middle point of the second series circuit is connected to a second terminal of the AC power supply. A current is controlled and outputted by PWM control such that a DC voltage of the smoothing capacitor can be maintained at a constant target voltage and the input power factor from the AC power supply is about 1, and a voltage generated on the AC side is superimposed onto an input voltage from the AC power supply. The short-circuit switch is turned on to bypass the smoothing capacitor, only in a short-circuit phase range centered at a zero cross phase of the phase of the input voltage from the AC power supply (for example, see Patent Document 1).